The present invention relates to the technology of supplying treating liquid to liquid treatment apparatus that applies a treating liquid such as a resist liquid upon a substrate, such as a semiconductor wafer or a glass substrate (LCD substrate) of liquid crystal display devices.
In the fabrication process of semiconductor devices, there is used an apparatus that applies a liquid treatment process to a surface of a semiconductor wafer (referred to hereinafter simply as “wafer”) by supplying thereto a treating liquid. Such liquid treatment process includes a treatment that uses a resist liquid as the treating liquid, a treatment that uses a developing liquid as the treating liquid, a treatment that uses a solution containing precursor of insulation film as the treating liquid, and the like.
In an example shown in FIG. 12, such a liquid treatment process is carried out in a liquid treatment apparatus 100 equipped with a liquid treatment unit 110a. In the liquid treatment unit 110a, a wafer W is held horizontally on a spin chuck 106 inside a cup 108 and the liquid treatment is carried out by ejecting a treating liquid from a supply nozzle 109 while rotating the wafer W by a drive mechanism 107.
Supply of the treating liquid to this liquid treatment unit 110a is achieved by using a supply unit 110b provided inside the liquid treatment apparatus 100. The supply unit 110b includes a supply tank 101 holding the treating liquid therein, a remaining amount detection tank 102, a filter 103 for eliminating impurities and bubbles in the treating liquid, a second trap 104 for eliminating bubbles passed through the filter 103 from the treating liquid, valves 102a-104a for discharging the bubbles from the vents provided thereto, and liquid feeding means to be explained below, wherein the supply tank 101, the remaining amount detection tank 102, the filter 103, the second trap 104, the valves 102a-104a, and the liquid feeding means are connected with each other by conduits. The liquid feeding means includes an air-operated valve 111b and a suck valve 111a and is capable of supplying the treating liquid to the supply nozzle 109 with a constant amount. Further, there is provided a pressurizing part 105 pressurizing the interior of the supply tank for pumping out the treating liquid.
As set forth in Patent Reference 1, the residual amount detection tank 102 detects, when the treating liquid inside the supply tank 101 has been used up and use of the treating liquid in the residual amount detection tank 102 has been started, that the supply tank 101 has been emptied and that the use of the treating liquid in the remaining amount detection tank 102 been has started by way of a liquid level sensor (not shown) provided to the remaining amount detection tank 102, and notifies this to operator.
On the other hand, the liquid treatment apparatus 100 of such a conventional construction is complex in that there are provided various parts such as the remaining amount detection tank 102, the filter 103, the second trap 104, and the like, in the manner that they are connected with each other by the conduits, while such a complex construction raises the problem of poor efficiency of maintenance work and high risk of causing liquid leakage for example at the joints used for connecting various parts to the conduits. Further, because the supply unit 110b includes a number of parts as noted above, there has been a difficulty of downsizing the coating and developing apparatus and reducing the space occupied by the coating and developing apparatus in which the liquid supplying apparatus 100 is used.
It should be noted that Patent Reference 1 discloses the technology of ensuring removal of bubbles in the resist liquid by applying a negative pressure to the resist liquid as it flows through a path in the supplying unit 110b such that the gases dissolved into the resist liquid are removed in the form of bubbles. Thus, this technology of Patent Reference 1 addresses a problem different from the problem of reducing the space occupied by the liquid treatment apparatus as in the case of the present invention.
Patent Reference 1 Japanese Laid-Open Patent Application 2000-12449